Julian T. Parer

Intrahepatic cholestasis of pregnancy: A retrospective case-control study of perinatal outcome

OBJECTIVES Intrahepatic cholestasis of pregnancy has been related to a high frequency of abnormal intrapartum fetal heart rate, amniotic fluid meconium, prematurity, and perinatal mortality. To determine whether these adverse perinatal outcomes could be improved with active intervention, we evaluated our results. STUDY DESIGN We report a retrospective case-control study of 320 consecutive patients with intrahepatic cholestasis of pregnancy management with antepartum testing and active intervention over a 2-year period. RESULTS Our results indicate a higher incidence of meconium staining in amniotic fluid at delivery (25% vs 16%, p < 0.05) and spontaneous preterm delivery (12.1% vs 3.9%, p < 0.05), without an increase in the frequency of abnormal intrapartum fetal heart rate (12% vs 11%, not significant), 5-minute Apgar score < 7 (2.0% vs 1.0%, not significant), or perinatal mortality (18/1000 vs 13/1000, not significant). CONCLUSION Antenatal testing and timed intervention of patients with intrahepatic cholestasis of pregnancy is associated with a reduction of the previously reported adverse perinatal outcomes.

Fetal heart rate monitoring: Is it salvageable?

Fetal heart rate monitoring was introduced in the 1960s. After a number of randomized controlled trials in the mid 1980s, doubt arose regarding the efficacy of fetal heart rate monitoring in improving fetal outcome. The potential reasons why fetal heart rate monitoring has not been shown to be efficacious are (1) use of an outcome measure that is not related to variant fetal heart rate monitoring patterns, (2) lack of standardized interpretation of fetal heart rate patterns, (3) disagreement regarding algorithms for intervention of specific fetal heart rate patterns, and (4) the inability to demonstrate the reliability, validity, and ability of fetal heart rate monitoring to allow timely intervention. A recent National Institutes of Health committee proposed detailed, quantitative, standardized definitions of fetal heart rate patterns, which can serve as a basis for determining whether fetal heart rate monitoring is reliable and valid. In this article we examine reasons why fetal heart rate monitoring did not live up to its original expectations and why the randomized controlled trials did not demonstrate efficacy, and we make suggestions for determining whether electronic fetal heart rate monitoring should be abandoned.

Forceps compared with vacuum: Rates of neonatal and maternal morbidity

OBJECTIVE: To compare perinatal outcomes between forceps- and vacuum-assisted deliveries. Our hypothesis was that the force vectors achieved in forceps delivery will lead to fewer shoulder dystocias, but greater perineal lacerations. METHODS: This was a retrospective cohort study of 4,120 term, cephalic, singleton, nonrotational operative vaginal deliveries at a single institution. Outcomes examined included rates of neonatal trauma, shoulder dystocia, and perineal lacerations. Potential confounders, including maternal age, birthweight, ethnicity, parity, station at delivery, episiotomy, attending physician, anesthesia, and length of labor, were controlled for using multivariate logistic regression. RESULTS: Among the 2,075 (50.4%) forceps- and 2,045 (49.6%) vacuum-assisted deliveries, the rate of shoulder dystocia was lower among women undergoing forceps delivery (1.5% compared with 3.5%, P < .001), as was the rate of cephalohematoma (4.5% compared with 14.8%, P < .001), whereas the rate of third- or fourth-degree perineal laceration was higher (36.9% compared with 26.8%, P < .001). These differences in perinatal complications persisted when controlling for the confounders listed above. The adjusted odds ratio for shoulder dystocia was 0.34 (95% confidence interval [CI] 0.20–0.57), for cephalohematoma was 0.25 (95% CI 0.19–0.33), and for third- or fourth-degree lacerations was 1.79 (95% CI 1.52–2.10) when comparing forceps to vacuum. CONCLUSION: Vacuum-assisted vaginal birth is more often associated with shoulder dystocia and cephalohematoma. Forceps delivery is more often associated with third- and fourth-degree perineal lacerations. These differences in complications rates should be considered among other factors when determining the optimal mode of delivery. LEVEL OF EVIDENCE: II-2

Fetal acidemia and electronic fetal heart rate patterns: Is there evidence of an association?

Objective. Despite the ubiquity of electronic fetal monitoring, the validity of the relationship between various fetal heart rate (FHR) patterns and fetal acidemia has not yet been established in a large unselected series of consecutive pregnancies. The aim of this study was to examine the published literature for evidence of such a relationship. Methods. Four hypotheses based on assumptions in common clinical use were examined. The literature was searched for relationships between certain aspects of FHR patterns (e.g., degree of FHR variability, depth of decelerations), and fetal acidemia, or fetal vigor (5-minute Apgar score ≥7). We also attempted to relate duration of these patterns to the degree of acidemia. Using standardized FHR nomenclature we defined patterns based on baseline FHR variability, baseline rate, decelerations, and accelerations. Results. The following relationships were observed: (1) Moderate FHR variability was strongly associated (98%) with an umbilical pH >7.15 or newborn vigor (5-minute Apgar score ≥7). (2) Undetectable or minimal FHR variability in the presence of late or variable decelerations was the most consistent predictor of newborn acidemia, though the association was only 23%. (3) There was a positive relationship between the degree of acidemia and the depth of decelerations or bradycardia. (4) Except for sudden profound bradycardia, newborn acidemia with decreasing FHR variability in combination with decelerations develops over a period of time approximating one hour. Most studies identified were observational and uncontrolled (grade III evidence of US Preventive Services Task Force); however, there was general agreement amongst the various studies, strengthening the validity of the observations. Conclusions. The validity of the relationship between certain FHR patterns and fetal acidemia and/or vigor, is supported by observations from the literature. In addition four assumptions commonly used in clinical management are supported. These conclusions need to be confirmed by a prospective examination of a large number of consecutive, unselected FHR patterns, and their relationship to newborn acidemia. Pending the completion of such studies, these observations can be used to justify certain aspects of current clinical management, and may assist in standardizing the diversity of opinions regarding FHR pattern management.

Physiologic and histologic changes in near-term fetal lambs exposed to asphyxia by partial umbilical cord occlusion

OBJECTIVES Our purpose was to characterize the histologic changes in the asphyxiated fetal lamb brain and to correlate the severity of these changes with fetal physiologic parameters during and after asphyxia. STUDY DESIGN Seventeen near-term fetuses were used for analysis: control group without manipulation (n = 4, 132 +/- 1.1 days of gestation at autopsy, mean +/- SEM), sham-asphyxia control group (n = 3, 132 +/- 1.3 days), and asphyxiated group, which successfully survived 72 hours after asphyxia (n = 10, 130 +/- 1.0 days). Asphyxia was produced by umbilical cord occlusion lasting for approximately 60 minutes until fetal arterial pH diminished to < 6.9 and base excess to < -20 mEq/L. Fetal heart rate, blood pressure, and electrocorticographic activity were continuously monitored. The fetuses were killed 72 hours after asphyxia, and the brains were fixed in formalin and processed for histologic and immunocytochemical studies. RESULTS Neuropathologic changes varied from case to case, ranging from almost total infarction of cortical and subcortical structures to extremely subtle and patchy white matter alterations characterized by slight vacuolization of the white matter or slight to moderate increases in cellularity confined to the junction of cerebral cortex and white matter. Even fetuses that showed full recovery of all physiologic parameters, including electrocorticographic activity, demonstrated subtle but distinct white matter lesions. The gray matter, including the hippocampal neurons, was generally spared in these cases. Electrocorticographic parameters, duration of hypotension during asphyxia, and delayed recovery of blood lactate concentrations correlated well with the histologic grading of brain damage. CONCLUSIONS Asphyxia by partial umbilical cord occlusion in near-term fetal lambs produces variable neuropathologic changes. The mildest change is a white matter lesion characterized by vacuolization and loss of myelin or by increased cellularity in the damaged regions.

Oral ritodrine maintenance in the treatment of preterm labor

Seventy patients with preterm labor and intact membranes were initially treated with ritodrine hydrochloride to delay preterm delivery. Tocolysis beyond 24 hours was achieved in 59 patients. Fifty-five of the 59 patients were then placed on either oral ritodrine or placebo as maintenance therapy in a randomized double-blind manner. If preterm labor recurred, the sequence of intramuscular and then oral treatment was repeated. The number of days gained after initiation of intramuscular treatment was similar in both groups (oral ritodrine = 34 days, oral placebo = 36 days). In those 55 patients receiving oral treatment, there was a smaller number of relapses requiring repeat intramuscular treatment in the oral ritodrine group (1.11 in the ritodrine patient vs. 2.71 in the placebo patient, p less than 0.05), and the mean interval between beginning oral treatment and the first relapse/delivery was 5.8 days in the oral placebo group and 25.9 in those receiving oral ritodrine (p less than 0.05). Cardiovascular side effects, notably maternal tachycardia and palpitations were frequent but well tolerated. The results suggest that oral ritodrine maintenance will decrease the incidence of recurrent preterm labor in patients who have had initial successful tocolysis.

Intrapartum management of category II fetal heart rate tracings: towards standardization of care

There is currently no standard national approach to the management of category II fetal heart rate (FHR) patterns, yet such patterns occur in the majority of fetuses in labor. Under such circumstances, it would be difficult to demonstrate the clinical efficacy of FHR monitoring even if this technique had immense intrinsic value, since there has never been a standard hypothesis to test dealing with interpretation and management of these abnormal patterns. We present an algorithm for the management of category II FHR patterns that reflects a synthesis of available evidence and current scientific thought. Use of this algorithm represents one way for the clinician to comply with the standard of care, and may enhance our overall ability to define the benefits of intrapartum FHR monitoring.

Validity of indications for transabdominal cervicoisthmic cerclage for cervical incompetence

OBJECTIVE Our purpose was to review the indications for transabdominal cervicoisthmic cerclage to determine whether it is a valid alternative to transvaginal cerclage. STUDY DESIGN A retrospective review of transabdominal cerclage patients at one institution from 1978 to 1994, analysis of the indications for the transabdominal rather than the vaginal approach, and evaluation of fetal outcomes was performed. RESULTS Twenty-three patients underwent 24 transabdominal cerclages. The primary indication for transabdominal cervicoisthmic cerclage was failed transvaginal cerclage in 14 patients and anatomic unsuitability for transvaginal cerclage in nine. Of the latter, five were a result of diethylstilbestrol exposure and four a result of cervical surgery. All patients were successfully delivered of one or more live babies (total 28, including two sets of twins). Two losses occurred, one after rupture of membranes at 21 weeks on the second pregnancy after cerclage placement and one intraoperative loss with herniation of the membranes. The live birth rate was 93%, compared with 18% salvage of pregnancies beyond the first trimester before the transabdominal cervicoisthmic cerclage procedure. Complications included blood loss requiring transfusion (four patients), although none of these occurred in the last 12 patients. CONCLUSION We conclude that all the patients had a history compatible with incompetent cervix requiring a cerclage, and none were suitable candidates for a vaginal cerclage. We further conclude that with strict indications transabdominal cervicoisthmic cerclage offers a high rate of fetal salvage with a minimum of complications in patients with extremely poor obstetric histories because of cervical incompetence.

The effect of acute maternal hypoxia on fetal oxygenation and the umbilical circulation in the sheep.

The mean oxygen consumption was 8.4 +/- 1.9 ml/min/kg in the near-term fetal sheep. In response to acute maternal hypoxia fetal O2 consumption decreased to lower than 50% of the control values. The decrease was rapidly instituted, proportional to the degree of hypoxia, sustained for up to 47 min and stable over this period. With increasing duration of hypoxia, a progressive metabolic acidosis developed. Recovery of oxygen consumption occurred rapidly after hypoxia ceased, though the acidosis was not resolved until 2 h later. Umbilical blood flow was maintained during maternal hypoxia and umbilical arterial and venous pressures increased. A fetal bradycardia invariably accompanied the hypoxia.

Validity of mathematical methods of quantitating fetal heart rate variability

Twenty-two mathematical formulas purporting to quantitate fetal heart rate variability, 13 for short-term and nine for long-term variability, were examined by using artificially generated numbers representing either short-term variability or long-term variability. Numbers representing short-term variability consisted of alternating beats, and those representing long-term variability were sine waves of differing amplitude or frequency spanning the generally accepted clinical range of fetal heart rate variability. The validity of the indices was determined by applying certain selected criteria. The results showed that 11 of the 13 short-term variability indices validly measured short-term variability, whereas only one of the nine long-term variability indices did so. The two major defects in the long-term variability indices were that there was an increase in the long-term variability index as the short-term variability increased, and the long-term variability indices did not increase linearly with increasing frequency of long-term variability complexes. This study suggests that short-term variability is relatively easy to quantify, but there is little relationship between the long-term variability indices and what is clinically regarded as long-term variability.